python异常

try:
 file = open("test1.txt","r")
 print(file.read())
 file.close()
# except Exception:
except (IOError,ZeroDivisionError):
    print("出错了")
print("哈哈哈哈哈")

try:
 file = open("test1.txt","r")
 print(file.read())
 file.close()
except IOError as result:
    print(result)

try:
    file = open("test1.txt", "r")
    try:
        print(file.read())
    except IOError as result:
        print(result)
    else:
        print("没有异常")
    finally:
        file.close()
except:
    print("文件出错了")

try:
    file = open("test1.txt", "r")
    try:
        while True:
            content = file.readline()
            if len(content) == 0:
                break
    except IOError as result:
        print(result)
    else:
        print("没有异常")
    finally:
        file.close()
except:
    print("文件出错了")

自定义异常
class ShortInputException(Exception):
   def __init__(self,length,atleast):
       self.length = length
       self.atleast = atleast
   def __str__(self):
       return "ShortInputException: 输入的长度是 %d,长度至少应是 %d" %(e.length,e.atleast)

try:
    s = input("please input:")
    if len(s) < 3:
        raise ShortInputException(len(s),3)
except ShortInputException as e:
    print(e)